Joy for Brazil as World Cup opens

Brazil's forward Neymar celebrates after scoring against Croatia during the opening match of the 2014 World Cup at the Corinthians Arena in Sao Paulo, on June 12, 2014

Brazil launched the World Cup with an emotion-fuelled 3-1 victory over Croatia on Thursday as an opening day which began with violent clashes gave way to an outpouring of joyful celebrations.

However, governing body FIFA look set to be under the spotlight again -- this time for events on the pitch -- as Japanese referee Yuichi Nishimura's awarding of a second-half penalty to Brazil was universally slammed with the 42-year-old receiving some of the sternest criticism in Japan.

The host nation's Group A victory was greeted by an explosion of fireworks across Sao Paulo, a sharp contrast to several hours earlier when riot police fired tear gas and stun grenades to disperse angry protests.

Croatia's Dejan Lovren (left) and Ivan Rakitic argue with Japanese referee Yuichi Nishimura during the opening match of the 2014 World Cup at the Corinthians Arena in Sao Paulo, on June 12, 2014

But a largely free-flowing tournament-opener was shrouded in controversy, with Brazil's second coming courtesy of a dubious penalty when Croatia defender Dejan Lovren was harshly adjudged to have shoved Fred.

The hosts, chasing a record sixth World Cup, had also enjoyed a degree of good fortune in the first half when Neymar received only a yellow card for elbowing Croatia's playmaker Luka Modric.

Moments later Neymar scored Brazil's equaliser to settle home nerves after Marcelo's 11th-minute own goal.

Brazilian football fans watch the opening match of the 2014 World Cup at a bar in Mogi das Cruzes, on June 12, 2014

Nishimura's performance comes as further embarrassment for FIFA after months of public protests and strikes in Brazil, and with soccer's ruling body battling renewed allegations of corruption over its award of the 2022 World Cup to Qatar.

The influential Jutarnji List daily slammed un "inexcusable mistake by the referee at the World Cup opening match" by which he "pierced Croatia's heart with a sword."

Anticipating further backlash against Nishimura, Japanese fan @tonbuhin tweeted: "Oh dear, if Brazil win the World Cup the whole world will say Nishimura was the MVP (most valuable player)."

- National pride -

(L-R) Singer Jennifer Lopez, rapper Pitbull and Brazilian pop singer Claudia Leitte perform during the opening ceremony of the Brazil World Cup at the Corinthians Arena in Sao Paulo on June 12, 2014

Pop superstars Jennifer Lopez and Pitbull headlined a lavish opening ceremony which included the appearance of a paraplegic wearing a robotic bodysuit controlled by brain signals who performed a ceremonial kick-off.

The match began after a hearty rendition of Brazil's national anthem with fans -- exhorted to unite behind the team by coach Luiz Felipe Scolari -- roaring their support for the "Selecao".

Even after the music stopped, fans and players belted out one more verse.

The victory provided a euphoric counterpoint to scenes earlier in the day when violent protests in Sao Paulo had threatened a stormy start to the month-long football extravaganza.

A Brazilian fan is seen during the match against Croatia at the Fan Fest in Rio de Janeiro, on June 12, 2014

It had been a torrid seven-year build-up bedevilled by delays and public anger at the tournament's $11 billion cost, and scattered protests took place Thursday in several of the cities which will host World Cup games.

The worst violence took place just a few kilometres from the opening match, as anarchist demonstrators in black shirts and masks lit bonfires of rubbish after armoured police sought to quell protests.

But Sao Paulo and other cities largely went quiet as the game started. Yellow and green flags hung from many buildings.

After the victory some fans expressed hope Brazil could rally behind the team's campaign.

- Tear gas fired -

Brazilian riot police detain a demonstrator during a protest against the World Cup in Belo Horizonte, on June 12, 2014

"This joy will be a contagion that will spread to all Brazilians," said Jonathan de Jesus Silva, 21, a nursing student. "This happiness will help bring a better climate."

Protesters who last year brought chaos to the Confederations Cup rehearsal tournament had vowed to march on the Sao Paulo stadium.

But riot police responded forcefully, chasing protesters up a main avenue and firing tear gas in the middle of oncoming traffic, forcing cars decorated with the Brazilian flag to weave their way through the chaos.

A cannister fired by police hit and injured a CNN journalist and an AFP correspondent saw one woman in tears clutching her arm.

In Rio de Janeiro, striking ground staff briefly blocked a road leading to the city's international airport.

Around 1,000 protesters also gathered in the city centre, a small group of them scuffling with police, who arrested four people.

A total of 64 games will culminate with the July 13 final in Rio de Janeiro's Maracana Stadium next month.

Friday's action promises more drama, with world champions Spain facing the Netherlands in a repeat of the 2010 World Cup final in the northern city of Salvador in Group B.

Group B's other encounter sees dark horses Chile take on Australia. In the day's other remaining game, Mexico play Cameroon in Group A.